Carbohydrate-boron alkoxide compounds

ABSTRACT

Fibrous cotton cellulose boron isoproxide or boron propoxide. Under anhydrous conditions, stable compounds of cotton cellulose and boron isopropoxide or boron propoxide were prepared in the neat boron alkoxide, the parent alcohol, benzene, pyridine, and/or ethylenediamine. The method of this invention has as its objective increasing the reactivity of the cotton cellulose with boron isopropoxide or boron propoxide by treatment in solutions of strong bases, such as pyridine and ethylene diamine. Formation of the fibrous cotton cellulose-boron isopropoxide or boron propoxide modifies the rate of oxidation of the cotton cellulose and is related to preparing flame resistant products.

United States Patent [191 Arthur, Jr. et a1.

represented by the Secretary of Agriculture, Washington, DC.

22 Filed: Oct. 15, 1973 21 Appl.No.:406,407

Related US. Application Data [62] Division of Ser. No. 256,021, May 23, 1972, Pat. No.

[52] US. Cl 260/212, 8/116 R, 8/196, 260/231 A [51] Int. Cl C08b 15/06 [58] Field of Search 260/212, 231 A; 8/116 R, 8/196 [56] References Cited UNITED STATES PATENTS 3,666,750 5/1972 Briskin et al 260/212 June 28, 1974 Primary Examiner-Melvyn I. Marquis Attorney, Agent, or Firm-M. Howard Silverstein; Max D. Hensley [57] ABSTRACT Fibrous cotton cellulose boron isoproxide or boron propoxide. Under anhydrous conditions, stable compounds of cotton cellulose and boron isopropoxide or boron propoxide were prepared in the neat boron alkoxide, the parent alcohol, benzene, pyridine, and/or ethylenediamine. The method of this invention has as its objective increasing the reactivity of the cotton cellulose with boron isopropoxide or boron propoxide by treatment in solutions of strong bases, such as pyridine and ethylene diamine. Formation of the fibrous cotton cellulose-boron isopropoxide or boron propoxide modifies the rate of oxidation of the cotton cellulose and is related to preparing flame resistant products.

4 Claims, No Drawings CARBOHYDRATE-BORON ALKOXIDE COMPOUNDS hereby granted to the Government of the United States of America.

This instant invention relates to a process for the preparation of carbohydrate-boron alkoxide products.

The method of this invention has as its objective increasing the reactivity of carbohydrates, particularly as their molecular weights increase, with boron alkoxides. As the molecular weight of the carbohydrate increased, its reaction with boron alkoxides neat, in benzene, or in the parent alcohol did not occur or decreased to a very low extent of reaction. It was found that in pyridine or ethylenediamine, the reactivity of carbohydrates toward boron alkoxides increased. Further it was observed thatcellulose did not react with the neat alkoxides and reacted with them in pyridine to only a small extent; in ethylenediamine cellulose, both ground and in fiber form, reacted-with the alkoxides.

Developments in the commercialv use of boron containing compounds, applied to cellulosic textile materials, to modify the rate of oxidation of textiles thereby imparting flame resistance to cellulosic products, have been reported in the literature. Also, the ionization of boric acid is increased in solutions containing carbohydrates. This effect has been used to separate borate complexes of carbohydrates by differential elution from columns of ion exchange resins or by paper ionophoresis. Alkyl borates of carbohydrates are used in Friedel-Crafts reactions to make useful organic compounds.

The instant invention defines methods for the preparation of stable compounds of methyl-a-D-glucoside, methyl a-D-mannoside, sucrose, cellobiose, methyl cellulose, and cellulose and boron alkoxides, such as boron ethoxide, boron propoxide, and boron isopropoxide. Unexpectedly, it was found that carbohydrates, having a high molecular weight such as purified cotton cellulose (molecular weight 700,000), could be reacted in strong bases, such as ethylenediamine, with boron alkoxides under anhydrous conditions to yield stable compounds. Reaction products of boron alkoxides and carbohydrates are apparently Lewis acids whose properties may be related to the electrophilic character of the glucopyranoside ring. Boron alkoxides are generally electron deficient and would tend to withdraw electrons from the glucopyranoside ring, normally an electron sink. These effects would likely decrease the rate of oxidation of the ring.

The following examples are provided to illustrate the invention and are not intended to limit the invention in any manner whatever.

EXAMPLE 1 Methyl-oz-D-glucoside (8 g) and boron isopropoxide (25 ml) were added to benzene (100 ml) in a flask (200 ml) fitted with a small column and distillation head.

The solution was then boiled at reflux; isopropanol formed was removed by azeotropic distillation. When isopropanol was no longer formed, the remaining volatiles were removed at 100C/0.3 torr. The solid product was analyzed. Anal. Calc. for [CH [C H O [B(OC H B, 6.13. Found: B, 6.12%. This product was soluble in benzene after 2 months of storage.

When this product was heated for about 2 hours at 100C/0.3 torr, 2 molecules condensed to yield boron isopropoxide and [B(OC H [B(OC H [CH l s v sl l 3 7)l [C6H7O6] 3] l 3 1)l [B(OC H Anal. Calc.: B, 6.38; OC H 48.8. Found: B, 6.43; OC H 49.1%.

EXAMPLE 2 Methyl-a-D-mannoside (5g) and boron isopropoxide (25 ml) were added to benzene (100 ml) in a flask as described above. The solution was then boiled at reflux; isopropanol formed was removed by azeotropic distillation. The remaining volatiles were removed at l00C/0.3 torr. The solid product was analyzed. Anal. Calc. for [CH [C H O [B(OC H 8.6.13. Found: B, 6.09%. t

This product was dissolved in a minimum amount of benzene at 78C. Petroleum ether was added, until a small precipitate was formed. The solution was cooled to 25C, and a white product, yield about. 80 percent, was obtained. After isolation, this product was not completely soluble in benzene at 25C. The soluble fraction was recovered as solid after removing the benzene at 25C/0.3 torr. Anal. Calc. for [CH [C H O -[B(OC H B, 6.56. Found: B, 6.62%.

EXAMPLE 3A EXAMPLE 3B Sucrose (3 g) was dissolved in pyridine (35 ml) at C. Boron propoxide 25 ml) was added. Then the solution was allowed to stand overnight at 25C. A white solid product formed. The volatiles were removed at 50C/0.3 torr. The product was not soluble in benzene. When boron propoxide (10 ml) was added and the solution was heated to C, the product dissolved. The solution was filtered through a sintered glass apparatus. Then the volatiles were removed at 50C/0.3 torr. Anal. Calc. for [C H O [B(OC H B, 7.05. Found: B, 6.97%.

EXAMPLE 3C Sucrose (2 g) was dissolved in pyridine (25 ml) at 70C. Boron isoproproxide (20 ml) saturated with ethylenediamine was added at 70C. Then the solution was boiled at reflux for 10 h. The volatiles were removed at 60C/0.3 torr. The product was analyzed. Anal. Calc. for l m u nl 3 7)l4 l 2 2Hel N C H 8.68. Found: B, 6.84; N C l-l 8.91%.

EXAMPLE 3D Sucrose (2 g) was dissolved in ethylenediamine (15 ml) at 70C. Boron propoxide (25 ml) was added. On cooling a solid product formed. The clear supernatant was decanted, then the remaining volatiles were removed at'70C/0.3 torr. Anal. Calc. for [C I-1 l a 1)2l2.5 l 2 2 6l2.s 2 2 e 1797- Found: B, 3.33; N C H 17.67%.

EXAMPLE 4 ml); then the reaction mixture was heated at 90C for 2 h. The mixture-was cooled to 25C and the supernatant liquid decanted. The remaining volatiles were removed at 70C/0.3 torr. Ana1.Calc. for [C H,.,O [B(OC l-1 [B(OC H B, 7.69; OC H 44.82. Found: B, 7.76; OC H 47.35%.

EXAMPLE 5A Methyl cellulose (5 g) and boron ethoxide in ethanol .(75 ml of 70% solution) were added to benzene (100 ml) and then boiled at reflux. Ethanol was removed by azeotropic distillation. The remaining volatiles were removed at 100C/0.3 torr. Anal. Found: B, 6.98%. This concentration of B would require trisubstitution of cellulose, as follows: Calc. for [C,,H,,O,,] [B(OC H,-,) B, 6.76%. This would indicate that the methoxyl groups were cleaved during the reaction and removed as methanol from the solution. Alternatively, a boron ethoxide cyclic complex with methyl cellulose could be formed to yield a product containing the amount of B found.

EXAMPLE 5B1 Methyl cellulose (5 g) and boron propoxide (50 ml) were boiled at reflux (about 130C) for 5 hr. Then benzene (25 ml) was added, and the propanol removed by azeotropic distillation. The remaining volatiles were removed at 100C/0.3 torr. Anal. Found: B,'2.02%. This concentration of B would require as follows: Calc. for l 6 9.s 4.al l alm l a 1)210.5 B, 202%- EXAMPLE 5B2 The product of Example 5Bl was mixed with the distillate; and boron propoxide ml) was added. The mixture was boiled at reflux (about 130C) for 8 h. Anal. Found: B, 2.85%. This concentration of B would require, as follows: Calc. for {C,,H O., [OCH [B(OC;,H B, 2.83%. Repetition of the above procedure did not increase the concentration of B in the product.

EXAM PLE 5 B3 The product of Example 532 was mixed with pyridine ml) for 2 minutes and then boron propoxide (50 ml) was added. The solution was boiled at reflux (about 130C) for 1 h, and then distillate (25 ml) was collected dropwise. The remaining volatiles were removed at 100C/0.3 torr. Anal. Found: B, 4.10%. This 4 concentration of B would require complete substitutution, as follows: Calc. for [C H O [OCH l 3 7)2li.a 380%- EXAMPLE 5C1 Methyl cellulose (3.4 g), boron isopropoxed (25 ml) and pyridine (25 ml) were boiled at reflux for 2 minutes. Then the volatiles were removed at l00C/O.3

Itorr. Anal. Found: B, 3.50%. This concentration of B would require as follows: Calc. for [C H O l aliJ l 3 7)2l1.1 345%- EXAMPLE 5C2 The product of Example 5C1 was combined with the distillate and then boiled at reflux. About one-third of the distillate was collected dropwise; then the remaining volatiles were removed at 100C/0.3 torr. Anal. Found: B, 4.02; OC H 42.97%. These concentrations would require complete substitution, as follows: Calc. for [C6H9O4.3] l alm 3 1)2l1.3 B, OC H 4l.48%.

EXAMPLE 6A1 Cotton cellulose (3.5 g), ground to pass a 20-mesh screen, was added to pyridine (30 ml). After 15 minutes at 25C, boron propoxide (40 ml) was added, and

the mixture was boiled at reflux for 20 minutes. Then distillate (25 ml) was removed dropwise at 130C. The remaining volatiles were removed at C/0.3 torr. Anal. Found: B, 0.71%. This concentration of B would require, as follows: Calc. for [C H O l :r '/)2l0.i2 B,

EXAMPLE 6A2 EXAMPLE 6B Cotton cellulose (5 g) in fiber form was added to pyridine (50 ml). After 15 minutes at 25C, boron isopropoxide (50 ml) was added, and the mixture boiled at reflux for 4 h. Benzene (25 ml) was added, and the mixture was boiled at reflux for 3 h. The isopropanol formed was removed at azeotropic distillation. Then the mixture was boiled at reflux overnight (17 h). Benzene (25 ml) was added, and the isopropanol formed was removed by azeotropic distillation. The remaining volatiles were removed at 100C/0.2 torr. AnaLFound: B, 0.31%. This concentration of B would require, as follows; Calc. for [C6Hg 9505] [B(OC3H7)2]0 05I B, 0.32%.

EXAMPLE 6C Cotton cellulose (5 g) in fiber form was added to ethylenediamine (50 m1), benzene (100 ml), and ethanol (15 ml). The mixture was boiled at reflux for 5 h, during which time the water ethanol benzene azeotrope was removed by distillation. Then boron propoxide (50 ml) was added, and the mixture was boiled at reflux for 23 h. At this time boron propoxide (25 ml) was added,

and the mixture boiled at reflux for an additional 2 h. After cooling to 25C the liquid was decanted and the reaction product was washed three times with benzene (50 ml each time); the liquid was decanted after each washing. Then the product was washed with petroleum 5 boron propoxide having the empirical ether (50 ml). The liquid was decanted and the remaining volatiles were removed at 50C/O.3 torr. Anal. Found: B, 3.63; C N H 18.86%. These concentrations would require as follows: Calc. for [Cd-[ a 1)2l1.s 2 2 sl1.s 2 2 6s We claim: l. A process for making fibrous cotton celluloseboron isopropoxide having the empirical formula [C H O [B(OC H the process comprising:

a. immersing 5 g of cotton cellulose in 50 ml pyridine for about minutes at room temperature, b. adding about 50 ml of boron isopropoxide and refluxing the mixture for about 4 hours, c. adding about 25 ml of benzene and refluxing the mixture for about 3 hours,

d. removing the isopropanol formed by azeotropic distillation, e. refluxing the remaining mixture for about 17 hours, f. adding about 25 ml of benzene, g. removing the isopropanol formed by azeotropic distillation, and h. removing the remaining volatiles at 100C/0.3 torr.

2. The fibrous cotton cellulose-boron isopropoxide produced by the process of claim 1.

3. A process for making fibrous cotton celluloseformula i s ssosl a 1)2l1.s 2 2 el1.s the Process comprising:

a. immersing 5 g of cotton cellulose in a solution consisting of 50 ml ethylenediamine, 100 ml benzene, and 15 ml ethanol,

b. refluxing the mixture for about 5 hours during which time the water-ethanol-benzene azeotrope is removed by azeotropic distillation,

0. adding about 50 ml of boron propoxide and refluxing the mixture for about 23 hours,

d. adding about 25 ml boron propoxide and refluxing the mixture for an additional 2 hours,

e. cooling the mixture to room temperature and decanting the liquid,

f. washing the cellulose product several times with 50 ml portions of benzene and decanting the liquid off each time,

g. washing the cellulosic product with petroleum ether, and

h. removing the remaining volatiles upon heating the mixture at about 50C/0.3 torr.

4. The fibrous cotton cellulose-boron propoxide produced by the process of claim 3. 

2. The fibrous cotton cellulose-boron isopropoxide produced by the process of claim
 1. 3. A process for making fibrous cotton cellulose-boron propoxide having the empirical formula (C6H8.5O5) (B(OC3H7)2)1.5 (C2N2H6)1.5, the process comprising: a. immersing 5 g of cotton cellulose in a solution consisting of 50 ml ethylenediamine, 100 ml benzene, and 15 ml ethanol, b. refluxing the mixture for about 5 hours during which time the water-ethanol-benzene azeotrope is removed by azeotropic distillation, c. adding about 50 ml of boron propoxide and refluxing the mixture for about 23 hours, d. adding about 25 ml boron propoxide and refluxing the mixture for an additional 2 hours, e. cooling the mixture to room temperature and decanting the liquid, f. washing the cellulose product several times with 50 ml portions of benzene and decanting the liquid off each time, g. washing the cellulosic product with petroleum ether, and h. removing the remaining volatiles upon heating the mixture at about 50*C/0.3 torr.
 4. The fibrous cotton cellulose-boron propoxide produced by the process of claim
 3. 